It is well-established that humans lose a great amount of body heat through their heads when exposed to a cold environment. Likewise, the anatomical extremities—feet and toes, hands and fingers, noses, ears, etc.—lose heat more quickly than the body core, and are subject to frostbite and other dangerous conditions in cold environments if not protected. Additionally, when extremities such as fingers and toes become cold, numbness develops, motor functions and dexterity decline, and pain is amplified in response to even minor impacts. Therefore, cooling of the anatomical extremities substantially degrades human performance, comfort and safety.
Therefore, hats, hoods, balaclava, and other head coverings are employed in such conditions to provide an insulating layer, reducing the rate of heat loss through the head. Likewise, gloves, mittens, pockets, and other protective coverings are employed to prevent or delay heat loss through the extremities. However, protective, insulating coverings cannot maintain thermal stasis over time; they merely slow the rate of heat loss. Therefore, their benefit and effectiveness decreases over the course of extended exposure to ambient cold.
Furthermore, the effectiveness of hand coverings is frequently closely related to their thickness, which consequently negatively affects manual dexterity, as anyone attempting to remove car keys from their pocket while wearing gloves will readily recognize. When faced with the need to perform a manual task requiring dexterity while exposed in a cold environments, removing one's gloves is an intuitive and common response. However, manual dexterity is likewise reduced when the hands and fingers become cold due to such exposure. Therefore, performing dexterous tasks in cold weather remains a significant challenge, typically addressed by alternatingly exposing hands to perform tasks, then covering and warming them again to prevent discomfort and frostbite.
Perhaps man's oldest means for directly heating the extremities is the use of an open fire, perhaps followed by the placement of warmed rocks beneath blankets or into the clothing to provide a portable heating means. Indeed, protecting extremities from the cold by the use of protective coverings or the direct application of heat from an extrinsic source (e.g. fire), likely date from the dawn of man as a species.
Many devices have been developed and used over the years to provide direct and portable heating to the anatomical extremities. Such devices most typically include electrically-heated gloves, socks and boots; hand-held warmers utilizing electricity, combustible fuels, or chemical compounds reacting exothermically. However, in order to be effective, each extremity must be exposed to an associated heat source, requiring multiple devices each sized and configured sufficiently to deliver heating to a significant portion of a specific appendage. For example, shoes do not fit hands, and a left boot does not typically (comfortably) fit a right foot; therefore, each appendage requires a separate, specifically configured device to adequately deliver warming to that appendage. Further, because different types of outdoor activities frequently require differently configured types of footwear or hand coverings, the number, types, and costs of prior art extremity-warming equipment can rapidly escalate for an individual user.
While sufficient caloric consumption can help maintain body warmth via metabolic warming, the benefits of this heat source are likewise limited. Metabolic processes warm the body core to some extent, but the extremities benefit to a notably lesser extent due in part to the reduced rate and volume of blood flow as compared to the body core and the head. In particular, Caloric consumption diverts blood flow to the gastrointestinal tract for digestion, shunting blood from the periphery. Further, blood vessels in the extremities ordinarily constrict (i.e., vasoconstriction) when exposed to cold conditions in a natural response designed to help preserve the core body temperature.
Several related but distinct concepts are known in the art. For example, U.S. Pat. No. 6,792,624 to Simmons, entitled ‘Temperature Regulating Cap,’ (the '624 patent) describes that a head-worn, temperature-regulating cap can include a receptacle or pocket to accommodate an air activated heating pack. However, the '624 parent's expressed purpose is to heat the head of the user, and the heating pack is described as being placed in contact with the top of the user's head. The '624 patent neither describes positioning the heating source at, nor recognizes any benefit or design to provide for thermally affecting the extremities by heating applied to, a central portion of a user's forehead. Likewise, the '624 patent does not describe or contemplate any use of sensors for thermal regulation, nor a switched control for regulating the application of heat, nor a power source for extended use without the use of extrinsic reheating sources, nor numerous other of the beneficial features of applicants' invention described herein according to several embodiments.
Another device, known commercially as the HAMMACHER SCHLEMMER HEADACHE RELIEVING WRAP, the purpose of which is to relax tense muscles and thereby provide relief from migraine and tension headaches, likewise includes an insulated, size-adjustable headband used to retain reusable gel packs in proximity to a user's head. However, as with patent '624, this device also fails to comprehend any heating effect of the extremities, and does not include or disclose numerous other of the beneficial features of applicants' inventive embodiments.
Localized application of heat or cold has long been used to provide benefits to immediately affected portions of the head—e.g., for reduction or prevention of inflammation, headache relief, fever reduction, nausea reduction, to improve wakefulness, to stem a nosebleed, for general comfort, and other such uses. Scientific evidence shows that applying cold to the forehead decreases blood flow to the hands and feet, as documented in The Cold Pressor Test: Vascular and Myocardial Response Patterns and their Stability by Patrice G. Saab et al. (Psychophysiology, 30, pp. 366-373, Cambridge University Press (1993)). Applicants are unaware, however, of any recognition in the art of the use of heat applied to the central forehead region to specifically affect a beneficial warming response in the peripheral regions, particularly in the extremities such as the arms, hands, legs and feet.